1. Field of the Invention
The present invention relates to a method of recording additional data such as lyric and user input data to be in synchronization with audio data on a rewritable recording medium, and of reproducing them synchronously therefrom.
2. Description of the Related Art
A disk-type recording medium such as a Compact Disk (CD) can store high-quality digital audio data permanently, so that it is very popular recording medium in these days.
Recently, a Digital Versatile Disk (called ‘DVD’ hereinafter) has been developed as a new disk-type recording medium. A DVD can store much more data than a CD, that is, high-quality moving pictures or audio data are recorded on a DVD for much longer time. Therefore, a DVD will be used widely in the near future.
There are three types of DVDs—DVD-ROM for read-only, DVD-R for write-once, and DVD-RAM or DVD-RW for rewritable. For a rewritable DVD, the standardization of data writing format is in progress.
FIG. 1 is a block diagram of an optical disk device that records/reproduces audio data to/from a recording medium.
The disk device configured as FIG. 1 comprises an optical pickup 11 reading signals recorded on a rewritable DVD 10 such as a DVD-RW and writing data streams processed into writable signals onto the rewritable DVD 10; a reproduced signal processor 12 restoring the read signals into compressed digital data; a decoder 13 decoding the compressed digital data to original data; a sampler 18 digitizing an inputted analog signal at a preset sampling rate; an encoder 17 encoding the digitized LPCM data into MPEG-, or AC3-formatted data; a writing processor 16 converting the encoded data from the encoder 17 or LPCM data from the sampler 18 into signals suitable to be written; a controller 14 controlling all elements to conduct user's commands such as playback or record; and a memory 15 for storing data temporally.
If an analog signal is applied to the disk device of FIG. 1, the sampler 18 samples the analog signal at the preset sampling rate. Each sampled signal, which is LPCM data, is applied to the encoder 17 that encodes a block of sampled data into compressed data of pre-specified format, for example, MPEG format. The compressed data are then applied to the writing processor 16.
The writing processor 16 converts a series of the compressed data into binary signals which are written in mark/space patterns on the writable DVD 10. Already-compressed digital data from outside are directly processed by the writing processor 16 to be written onto the writable DVD 10.
After recording of audio data, navigation data for the audio data are created and then recorded on the writable DVD 10.
FIG. 2 shows the structure of RTR_AMG (Real Time Record Audio Management) recorded as navigation data on a rewritable disk. The RTR_AMG includes RTR_AMGI (RTR Audio Manager General Information), AUDFIT (AUDio File Information Table), ASVFIT (Audio Still Video File Information Table), ORG_PGCI (ORGiginal PGC (ProGram Chain) Information), UD_PGCIT (User Defined PGC Information Table), TXTDT_MG (TeXT DaTa ManaGer), and MNFIT (MaNufacturer's Information Table).
The TXTDT_MG can include additional data of recorded songs such as lyrics. Therefore, when the controller 14 selects and reproduces a recorded song from the rewritable disk 10, it is able to present lyric text in characters on a screen by reading it from the TXTDT_MG.
Consequently, when a user selects a recorded song to play back from the rewritable DVD 10, he or she is able to view its lyric on a screen.
However, each of additional data such as a lyric included in the TXTDT_MG is linked with a recorded song wholly. In other words, a lyric in the TXTDT_MG cannot have information to synchronize in detail with a recorded song. Therefore, it is impossible to display lyric data step by step at the same speed that the recorded song is reproduced from a rewritable DVD.